TY - JOUR

T1 - Nematic order condensation and topological defects in inertial active nematics

AU - Saghatchi, Roozbeh

AU - Yildiz, Mehmet

AU - Doostmohammadi, Amin

PY - 2022/7/25

Y1 - 2022/7/25

N2 - Living materials at different length scales manifest active nematic features such as orientational order, nematic topological defects, and active nematic turbulence. Using numerical simulations we investigate the impact of fluid inertia on the collective pattern formation in active nematics. We show that an incremental increase in inertial effects due to reduced viscosity results in gradual melting of nematic order with an increase in topological defect density before a discontinuous transition to a vortex-condensate state. The emergent vortex-condensate state at low enough viscosities coincides with nematic order condensation within the giant vortices and the drop in the density of topological defects. We further show flow field around topological defects is substantially affected by inertial effects. Moreover, we demonstrate the strong dependence of the kinetic energy spectrum on the inertial effects, recover the Kolmogorov scaling within the vortex-condensate phase, but find no evidence of universal scaling at higher viscosities. The findings reveal complexities in active nematic turbulence and empha-size the important cross-talk between active and inertial effects in setting flow and orientational organization of active particles.

AB - Living materials at different length scales manifest active nematic features such as orientational order, nematic topological defects, and active nematic turbulence. Using numerical simulations we investigate the impact of fluid inertia on the collective pattern formation in active nematics. We show that an incremental increase in inertial effects due to reduced viscosity results in gradual melting of nematic order with an increase in topological defect density before a discontinuous transition to a vortex-condensate state. The emergent vortex-condensate state at low enough viscosities coincides with nematic order condensation within the giant vortices and the drop in the density of topological defects. We further show flow field around topological defects is substantially affected by inertial effects. Moreover, we demonstrate the strong dependence of the kinetic energy spectrum on the inertial effects, recover the Kolmogorov scaling within the vortex-condensate phase, but find no evidence of universal scaling at higher viscosities. The findings reveal complexities in active nematic turbulence and empha-size the important cross-talk between active and inertial effects in setting flow and orientational organization of active particles.

KW - TURBULENCE

KW - STATISTICS

KW - VISCOSITY

KW - MECHANICS

KW - DYNAMICS

U2 - 10.1103/PhysRevE.106.014705

DO - 10.1103/PhysRevE.106.014705

M3 - Journal article

C2 - 35974636

VL - 106

JO - Physical Review E

JF - Physical Review E

SN - 2470-0045

IS - 1

M1 - 014705

ER -